JBL Hydro-Seals utilize an advanced multi-baffle polymer design providing exceptional protection against water entering the ear canal. In addition to greatly reducing the chance of infection by inhibiting bacteria from growing in stagnant inner-ear water, Hydro-Seals also help prevent the temporary loss of equilibrium. Simple and effective to use,Hydro- Seals reduce the chance of surfer’s ear by sealing out cold air and water, which causes exostosis.  Exclusive Hocks Noise Braker allows normal sound waves to pass through while preventing pressure build-up from water intrusion. Making them ideal for divers that have trouble clearing their ears at descending depths. - Fitting Guide available under Tech Tips page.